title: The effects of red-cell scavenging, hemodilution, and active warming on allogenic blood requirements in patients undergoing hip or knee arthroplasty.
abstract: Since 1993, we have progressively adopted three techniques to reduce transfusion requirements during major orthopedic surgery: red-cell scavenging, acute normovolemic hemodilution, and active patient warming. We retrospectively evaluated all 821 elective hip and knee arthroplasties performed in our institution beginning with July 1993. Target minimal hematocrits were guided by patient ages and cardiovascular status. The first approximately 500-mL blood loss was replaced with crystalloid at a ratio of 3 mL for each milliliter of blood loss. Additional blood loss was replaced with colloid, hemodilution blood (when available), and scavenged red cells (when available). Allogenic transfusions were then administered as necessary to maintain target hematocrits, which were prospectively defined based on the patient ages and cardiovascular health. Univariate analysis was applied initially. Significant predictors of transfusion requirement were subsequently entered into a stepwise multiple regression to account for confounding factors, including age, type of anesthesia (regional versus general) and type of surgery (primary versus hardware replacement). Postoperative hemoglobin concentrations were similar over the years of study and among the patients given each treatment. During the study period, allogenic blood requirements decreased from 1.3 +/- 1.7 U/patient to 0.6 +/- 1.4 U/patient (mean +/- SD). Both univariate and regression analyses indicated that each treatment significantly reduced transfusion requirements (P < 0.05). We conclude that red-cell scavenging, hemodilution, and active cutaneous warming each reduce allogenic blood requirements during hip and knee arthroplasties.
  
  
  CONCLUSIONS
  We retrospectively evaluated three strategies to reduce overall blood loss: red-cell scavenging, acute normovolemic hemodilution, and active patient warming. During the study period, allogenic blood requirements decreased by a factor of 2. Each treatment contributed to this reduction. We therefore conclude that each treatment reduces allogenic blood requirements during hip and knee arthroplasties.
authors.affiliation: Department of Anesthesiology, The General Hospital of Amstetten, Austria. 101364.3264@CompuServe.com
authors.forename: H
authors.initials: H
authors.lastname: Schmied
authors.forename: A
authors.initials: A
authors.lastname: Schiferer
authors.forename: D I
authors.initials: DI
authors.lastname: Sessler
authors.forename: C
authors.initials: C
authors.lastname: Meznik
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001793:Blood Preservation / Q000379:methods; D001803:Blood Transfusion; D001810:Blood Volume; D001831:Body Temperature; D006438:Hemodilution; D006801:Humans; D008875:Middle Aged; D012189:Retrospective Studies